Modeling And Analysis Of Steel Cable With Absolute Nodal Coordinate Formulation

The transmission system of steel cable structure has the characteristics of light weight and flexible arrangement of space,which is widely used in the long distance transmission control system of aircraft.But as the structure of steel cable is formed by multi strands,it has high tensile stiffness and little flexural stiffness.The cable will show large deformation of rotation under tensile load,causing the change of structural stiffness with the vibration of the load.As a result.It is difficult to predict the deformation and lag time of the cable structure under long distance transmission,which will directly affect the reliable and precision of control system.Therefore,it is very important to establish a model for accurately describing the deformation and dynamic characteristics of steel cables,and to study the mechanical properties of steel structures under different structural parameters.In this paper,the absolute nodal coordinate method is used to describe the rotational deformation of steel cables in the form of deformed slope coordinates.Considering the stiffness variation characteristics during the tension process of steel cables,a deformation and dynamic analysis model of steel cables is established.Studying on the deformation and dynamics of steel cables under different structural and mechanical parameters.The steel cable element model is applied to a certain aircraft control system model,and the terminal deformation and time lag characteristics of the control system under different parameters are analyzed.The parameters optimization design is carried out by orthogonal test analysis.The research results provide guidance for the modeling and analysis of the steel cable structure of the aircraft soft control system.The main contents include the following parts:(1)Dynamic model of steel cable structure systemBased on the absolute nodal coordinate method,the finite rotation deformation of the cable element under tensile load is described by the coordinate of the deformation slope,and the finite element for the numerical analysis of the cable is established.Based on the theory of continuous medium mechanics,the element stiffness matrix and mass matrix are derived.The vertical modulus of the cable is introduced and the average equivalent elastic modulus of the cable under the load is derived through the deflection coefficient.The deformation and dynamic equations of steel cables are established.By establishing Simulink model,the deformation characteristics of cables under axial load are calculated,and the rationality of the modeling is verified by comparing with experimental data.(2)Influence of different parameters on the deformation and dynamic characteristics of steel cablesThe deformation characteristics and dynamic characteristics of steel cable element structure and cable-pulley structure under different parameters are studied.Under the axial load of cable tension with the deformation rate increases,more sensitive to changes in small diameter steel cable tension,initial tension and length of cable has little effect on the elongation of the cable;cable lag time with axial load increases,the increase of the elastic modulus can improve the response speed of the system,the other parameters had little effect on the lag time of cable.(3)Typical soft aircraft control system and orthogonal testThe model of a typical soft aircraft control system is established,and the correctness of the model is verified by comparing the simulation results with the experimental data.Based on the basic principle and analysis method of orthogonal experimental design method,the orthogonal test scheme is designed for the dynamic and kinematic optimization design requirements of typical aircraft control system.By using the intuitive and variance analysis methods,the significant factors that affect the stiffness and the output friction of the whole control system are determined.The optimization design is given according to the design index of the control system.